The present invention is in the field of formed ceramic devices and the method of manufacturing same such that the ceramic devices may be used, for example, as a tube wall in an image intensifier as an extended leakage current path for high voltage application across narrow cathode-anode spaced (0.75mm-1.0mm) proximity focused image intensifier tube with increased high voltage stability due to runaway leakage current breakdown. The prior art cured ceramic tubes were either machined into some special form, or the green or uncured ceramics were molded into desired forms by pressing the green or uncured ceramic slurry against a mold. Both the machining method and the prior art molding method had the disadvantage of leaving surfaces on the ceramics that were rougher than were tolerable for use in the high electric field devices, such as in proximity focused image intensifier tubes. Prior art machining methods generally left the tube wall surfaces much rougher than possible to produce with ceramics having grain sizes on the order of 0.05 to 50 micrometers. This deficiency is corrected by the monomolecular surface smoothness of only 5 to 10 millimicrons of suitably fabricated plastic molds.